The ²⁴Mg(¹⁶O, ¹⁶O') reaction and triaxial structures in ²⁴Mg

Angular distributions for the elastic and inelastic scattering of ¹⁶O from ²⁴Mg, exciting the 2₁⁺ (1.37 MeV), 4₁⁺ (4.12 MeV) and 2₂⁺ (4.24 MeV) states, have been measured at E_c.m. = 43.5 MeV, an energy at which resonance-like structure has been observed previously in the related ²⁴Mg(¹⁶O, ¹²C)²⁸Si reaction. In particular, the 4₁⁺, 2₂⁺ doublet has been resolved for the first time for heavy-ion projectiles. The data have been well described by coupled-channels calculations within the framework of a Davydov-Filippov asymmetric rotor model for the low-lying states of ²⁴Mg, which has been extended to include a symmetric hexadecapole shape component. The optical model potential for the ¹⁶O + ²⁴Mg interaction was found to have a moderate real well depth and some surface transparency. The shape parameters for the nuclear potential were determined to be β^(N)₂ = 0.25, γ = 22° and β₄^(N) = -0.065 and the corresponding deformation lengths are in good agreement with earlier light-ion results. The inclusion of a negative symmetric hexadecapole component leads to an improved description of the reduced transition rates. The triaxial structure of ²⁴Mg is discussed.